1. Technical Field
Photoresist additives for preventing acid migration and photoresist compositions containing the same are disclosed. More specifically, photoresist additives are disclosed which prevent acid generated in an exposed area during the course of a photolithography process from diffusing or migrating to an unexposed area. Photoresist compositions containing the same and a process for forming a photoresist pattern using the same are also disclosed.
2. Description of the Related Art
Recently, chemical amplification-type DUV (deep ultra violet) photoresists have proven to be useful in achieving high sensitivity in processes for forming ultrafine patterns in the manufacture of semiconductors. These photoresists are prepared by blending a photoacid generator with a polymer matrix having acid labile structures.
According to the reaction mechanism of such a photoresist, the photoacid generator generates acid when it is irradiated by the light source, and the main chain or branched chain of the polymer matrix in the exposed or irradiated portion reacts with the generated acid and is decomposed or cross-linked, so that the polarity of the polymer is considerably altered. This alteration of polarity results in a solubility difference in the developing solution between the irradiated exposed area and the unexposed area, thereby forming a positive or negative image of a mask on the substrate.
It is necessary to prevent acid generated in the exposed area during the course of a photolithography process from diffusing or migrating to the unexposed area so as to improve resolution of the resulting pattern and to obtain a superior profile.
In order to prevent the acid diffusion, an amine or amide compound has been added to a chemical amplification type photoresist composition with an amount ranging from 5 to 30% per mole of the photoacid generator.
However, excessive use of amine or amide has caused light absorbance and optimum irradiation energy to increase, thereby deteriorating the productivity of the exposing process.
Moreover, a line edge roughness (hereinafter, abbreviated as xe2x80x98LERxe2x80x99) between 10-20 nm has been commonly shown in forming photoresist pattern of 110 nm or less, leading to inefficiencies in the process and final products with reduced stability.
Accordingly, photoresist additives are disclosed which can prevent diffusion of acid generated in the exposed area effectively. Photoresist compositions containing the same are also disclosed.
A process for forming an ultrafine pattern by using the disclosed photoresist compositions and a semiconductor element manufactured according to the disclosed process are also disclosed.